Research has been conducted for a number of years to detect early perceptual changes caused by subtle neurobiological alterations (NBAs) such as normal aging, neurotoxicity, glaucoma and more recently autism, fragile x, mild brain injuries and stroke.
The rationale for these studies was to fill a void of scientific knowledge related to perceptual functions, which resides between basic sensory measures, such as visual acuities, and higher cognitive measures such as neuropsychological profiles. Basic sensory measures are used to establish the attenuation of peripheral sensory mechanisms of the eye and ears while higher cognitive measures attempt to characterize cortical anomalies or symptoms. In fact, perceptual processing precedes cognitive processing and is often considered to be low-level cognitive processing although it is never systematically and explicitly assessed in neurological or neuropsychological evaluations.
Over the years, substantial evidence has been accumulated that, under appropriate conditions, perceptual changes are very good measures of neurobiological alterations and are resistant to lower-level and higher-level confounds in aging (Faubert, (2002)). In recent years, it has also been demonstrated that perceptual assessment techniques are also very sensitive to other NBAs such as autism (Bertone, Mottron, Jelinic, Faubert ((2003) and (2005))), fragile x (Kogan, Bertone, Cornish, Boutet, Der Kaloustian, Andermann, Faubert, Chaudhuri (2004)) and mild traumatic brain injuries (Brosseau-Lachaine, Gagnon, Forget & Faubert (2008)).
To introduce such measures in the clinical environment, it was proposed to develop visual charts for assessing both simple and complex perceptual processing. The problem with such charts is one of calibration of the image to obtain appropriate and constant linearization, levels of contrast, and the fact that it is not possible to establish perceptual signatures as described below because both static and dynamic stimuli are needed.
Accordingly, there exists a need for a device and method to implement measures of neurobiological alterations in the clinical environment and for various applications.